Is Testosterone Therapy Safe?

American men are three to four times more likely to be undergoing testosterone therapy (usually prescription gels or patches) than a decade ago, according to a recent study in JAMA Internal Medicine, which looked at data on more than 10 million men over 40. Men in their sixties have the highest usage rate—nearly 4 in 100 are taking the hormone. But even in men in their forties, who are less likely to have low blood levels of the hormone, there has been a spike in usage (2 in 100 take the hormone).

What’s especially troubling is that about 25 percent of men prescribed testosterone did not have their blood levels tested first. And it’s unclear how many of the men who were tested actually had low testosterone.

Men generally experience a slow but steady decline in testosterone, mostly after age 50. If a man’s testosterone level drops substantially and this causes adverse effects, it’s called late-onset hypogonadism, though there’s much controversy about how to define this and thus how common it is.

Drug companies and “anti-aging” clinics have been eager to medicalize low testosterone as the key sign of “andropause” (“male menopause”) and to market remedies for it. Ads (“Is It Low T?”) make it sound as if most older men should take testosterone to regain youthful vigor, have better erections, build muscle, improve mood and so on.

Testosterone: some key points

Though expert groups have come up with various sets of age-related ranges of “normal” blood levels of testosterone, no one knows what’s optimal. Levels can vary greatly from man to man, from day to day, and even during the course of the day.

However it’s defined, low testosterone is not a problem unless it is accompanied by undesirable symptoms, such as low sexual desire and erectile dysfunction. That’s why most guidelines require such symptoms for a diagnosis of age-related hypogonadism. The new study found that only half of men prescribed testosterone had been diagnosed with hypogonadism. Keep in mind that many, if not most, men who have sexual symptoms have “normal” levels of testosterone. And most men with low testosterone levels suffer few, if any, related problems.

Some genetic disorders and other conditions (notably pituitary, testicular or advanced liver disease), as well as certain medications, can result in a significant drop in testosterone. In those cases, men may benefit from testosterone therapy.

Testosterone therapy can cause acne, unwanted hair growth and breast enlargement. Of greater concern, it has been linked to an increased risk of heart disease, prostate cancer and liver damage, though the evidence for some of these risks is inconsistent. There have not been any large, long-term clinical trials on testosterone therapy along the lines of the famous Women’s Health Initiative study on menopausal hormone therapy. That study upended many hopes and beliefs when it found that the hormones posed serious risks.

Bottom line: There’s no convincing evidence that testosterone therapy benefits men who do not have laboratory-confirmed hypogonadism or certain medical conditions. Starting it is a serious decision, since the long-term risks are unknown. Do so only on expert medical advice. Don’t assume you need more testosterone just because you feel tired or your libido is dropping off—or because an ad or clinic presents it to you as a fountain of youth.